Heat exchanger

ABSTRACT

A heat exchanger for an internal combustion engine includes a base tube having opposite ends, and tube plates respectively provided at the ends of the base tube. A ring embraces the base tube. The ring is made of sheet metal and has legs extending toward one another in a V-shaped manner. An end cap is provided in the region of each tube plate and has a circumferential outwardly directed rim which is embraced by a tension element and connected to the ring.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Patent Application, Serial No. 10 2010 025 031.7, filed Jun. 24, 2010, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a heat exchanger.

The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.

Heat exchangers are used for example to recover heat or to cool recirculated exhausts of an internal combustion engine. By recirculating exhaust gas back to the combustion air, the proportion on nitrogen oxides in the exhaust that are harmful to the environment is decreased in particular when using lean mixtures in combination with high combustion temperatures.

Exhaust gas cooled down by the heat exchanger and fed to the combustion process reduces the air surplus contained in fresh air and lowers the combustion temperature at the same time so as to establish a combustion that contains significantly less pollutants. The mixture expanded by non-combustible fractions permits a lowering of the specific fuel combustion in particular in partial load operation of the motor.

Exhaust gas contacts a cooling fluid inside the heat exchangers in the absence of thorough mixture, resulting in an exchange of a temperature differential between the two fluids. The efficiency of the heat exchanger is determined by the surface area available for the temperature exchange. In order to configure the exchanger surface area as large as possible despite small outer dimensions, a number of exhaust-conducting tubes are arranged for example inside the heat exchanger and swept around circumferentially by the cooling fluid. A base tube is hereby provided which is connected at each end thereof by a tube plate. The exhaust-conducting tubes inside the base tube are combined to form a tube bundle which extends within the base tube between the confronting tube plates and is connected thereto. The base tube connected with the tube plates forms a chamber through which the cooling fluid flows and which are passed by the exhaust via the tube bundle.

It would be desirable and advantageous to provide an improved heat exchanger to obviate prior art shortcomings.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a heat exchanger for an internal combustion engine includes a base tube having opposite ends, tube plates respectively provided at the ends of the base tube, and a ring embracing the base tube, the ring being made of sheet metal and having legs extending toward one another in a V-shaped manner.

The ring has a contour which follows a contour of the base tube that is surrounded by the ring. This results in a lightweight structure with little material use. Both legs rest with their respective ends on the base tube, thereby preventing the ring from tilting.

According to another advantageous feature of the present invention, at least one of the legs may bear flatly upon the ring.

According to another advantageous feature of the present invention, the ring may be arranged between the tube plates. By coupling the heat exchanger with neighboring components via an additional structural part in the region of the ring, a balanced securement with respect to weight distribution is attained. Possible length variations of the heat exchanger as a result of thermal stress are thus shifted in approximately equal parts to the right and left sides of the rings so that increased stress of connecting structures are reduced to only one end of the base tube.

According to another advantageous feature of the present invention, the ring can have a bridge to connect respective ends of the legs to one another. The presence of the bridge further distances the legs and provides the V-shaped ring with a flat tip. The bridge distances the line contact of both legs with the base tube relative to one another so as to further secure the ring against tilting on the base tube. Moreover, the bridge reduces the size compared to a cross sectional shape with pointed end. Although both legs may have different lengths, an identical configuration is currently preferred.

According to another advantageous feature of the present invention, the ring can have a circular ring shaped configuration. This simplifies manufacture of the ring. For example roll forming may produce the circular ring shape as well as also the V-shaped cross section which in the form of a bent strand is connected to one another at the respective ends.

According to another advantageous feature of the present invention, the legs have bridge-distal ends which can have flanges that point away from one another. The flanges enable surface contact of the ring with the base tube to thereby provide the ring with a cross sectional shape which is suited to the base tube. Moreover, the section modulus of the ring transversely to its length axis is increased.

According to another advantageous feature of the present invention, the ring may be connected to the base tube by a material joint. The material joint may be provided in spots or also across the entire contacting circumference of the ring with the base tube. The connection may be realized for example by gluing or welding as well as soldering.

According to another advantageous feature of the present invention, the ring may be formed out of the base tube. This can be realized by providing the circumferential wall surface of the base tube with a circumferential protrusion so that the inner circumference of the base tube is enlarged in the region of the ring. This configuration eliminates the need for a separate connection between the ring and the base tube. Apart of the saved connection, the material use is further decreased accompanied with saving of an additional production of the ring separated from the base tube.

According to another advantageous feature of the present invention, an end cap can be arranged in a region of one of the tube plates. The end cap may be provided with an outwardly directed rim which can be embraced by a detachable tension element and connected to the ring. As a result of its V-shaped cross section, the ring is thus able to spontaneously center itself in relation to the tension element.

The shape of the rim substantially conforms to the configuration of the legs of the ring. The rim of the end cap establishes a circumferential flat contact toward the ring.

The tension element can also have a substantially V-shaped configuration in cross section and has a free end which grips around one of the legs of the ring and the rim of the end cap bearing upon the opposing leg. The tension element may have an open ring shape to define two ends which are connected with one another via a detachable connection element. Advantageously, the detachable connection element may be configured as a screw fastener, whereby a turning of the screw fastener can decrease or increase the circumference of the tension element. As the circumference of the tension element decreases, the V-shaped cross section of the tension element is pushed over the ring as well as over the rim of the end cap to press them against one another.

The tension element is connected with a neighboring structural part so that the heat exchanger is fixed in place via the tension element. Loosening the connection element opens the tension element whereupon the heat exchanger is liberated and can be removed from its embracement. At the same time, the connection between the end cap, connected via the ring with the base tube, and the heat exchanger is no longer effective. This results in a reduction of labor costs during replacement or maintenance works because the heat exchanger can be removed and at the same time opened when the connection element is loosened.

According to another advantageous feature of the present invention, a circumferential sealing element may be arranged between the rim of the end cap and the ring. The sealing element may be made of permanently elastic material or of metal or a combination of both. Turning the detachable connection element to change the circumference of the tension element causes a compression of the sealing element between one leg of the ring and the rim of the end cap to thereby increase the sealing action of the sealing element.

In accordance with the present invention, a heat exchanger is realized having a ring which is of simple structure and lightweight and can be produced in an economical manner. A configuration in which the ring is simply configured as a circumferential projection of the base tube is advantageous because it does not require additional material and respective manufacturing processes. As a result of the small contact area between the ring and the base tube, transmission of heat of the heat exchanger, generated by hot exhaust, to neighboring components is reduced. Overall, the weight is reduced and the manufacture is cost-efficient.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

FIG. 1 is a side view of an exemplary heat exchanger;

FIG. 1 a is a plan view upon one end of the heat exchanger of FIG. 1;

FIG. 2 is a schematic illustration of another embodiment of a heat exchanger;

FIG. 2 a is a plan view upon one end of the heat exchanger of FIG. 2;

FIG. 3 is a schematic illustration of yet another embodiment of a heat exchanger;

FIG. 3 a is a plan view upon one end of the heat exchanger of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

Turning now to the drawing, and in particular to FIG. 1, there is shown a side view of an exemplary heat exchanger, generally designated by reference numeral 1 and including a base tube 2 having opposite ends, each end being provided with a tube plate 3. The base tube 2 has a generally cylindrical cross section, with the tube plates 3 embracing the ends of the base tube 1. The tube plates 3 are formed with an edge 4 which extends at a right angle and circumferentially about the tube plates 3. The edge 4 has an inner circumference which corresponds to an outer circumference of the base tube 2 so that the tube plates 3 are placed with their edges 4 over the base tube 2 in a formfitting manner.

FIG. 1 a is a plan view upon one end of the heat exchanger 1 to show the respective tube plate 3. It can be seen that the tube plate 3 has a plurality of openings 5 of circular cross section. Placed within the openings 5 are individual tubes 6 which jointly establish within the base tube 2 a tube bundle, which is generally designated by reference numeral 7 and extends between the tube plates 3 and which is supported in the opposite openings 5.

Referring now to FIG. 2, there is shown a schematic illustration of another embodiment of a heat exchanger in accordance with the present invention, generally designated by reference numeral 50. The heat exchanger 50 includes a base tube 20 and a ring 8 which is wrapped around the base tube 20. The ring 8 has two legs 9 which extend towards one another in the shape of a V to provide the ring 8 with a substantially V-shaped configuration in cross section. The legs 9 are connected to one another by a bridge 19 at the outer circumference of the ring 8. Formed on their bridge-distal ends, the legs 9 are provided with flanges 11, respectively, which point away from one another. As shown in FIG. 2 a, the ring 8 has a circular configuration.

The ring 8, comprised of the legs 9, bridge 10, and flanges 11, is made from a single metal sheet. The ring 8 is in flat contact via the flanges 11 with the base tube 20 so that the ring 8 tapers in V-shaped manner towards its outer circumference in a direction of the bridge 10.

End caps 12, 13 are arranged in the region of the tube plates 3, respectively, and have an edge analogous to the tube plates 3. The end cap 13 includes a circumferential rim 14 which is directed outwards to provide contact of the end cap 13 with the neighboring one of the legs 9 of the ring 8. This leg 9 and the rim 14 have corresponding inclinations. The rim 14 and the ring 8 are both embraced about their circumference by a detachable tension element 15. A sealing element 16 is arranged between the ring 8 and the rim 14 of the end cap 13.

FIG. 3 shows another embodiment of a heat exchanger, generally designated by reference numeral 50 a. In the following description, parts corresponding with those in FIG. 2 will be identified by corresponding reference numerals followed by an “a”. In this embodiment, provision is made for a ring 8 a which is formed out of a base tube 20 a. The ring 8 a thus is configured as a circumferential projection which protrudes out of a peripheral surface of the base tube 20 a. The ring 8 a, like the ring 8 of FIG. 2, has legs 11 a extending towards one another in the shape of V and connected at the outer circumference of the ring 8 a by a bridge 10 a. The inner circumference of the base tube 20 a is enlarged in the region of the ring 8 a, with the wall of the base tube 20 a being deflected outwards.

In the assembled state of the heat exchangers 50, 50 a, the tension element 15 is guided around the ring 8, 8 a which is connected directly or indirectly with components of a motor vehicle for example. The tension element 15 also establishes a connection between the base tube 20, 20 a and the end cap 13. For that purpose, the end cap 13 is provided with the circumferential outwardly directed rim 14 which is connected via the tension element 15 with the ring 8, 8 a. The sealing element 16 is placed between the ring 8, 8 a and the rim 14 of the end cap 3.

During operation, hot exhaust flows for example through the heat exchanges 1, 50, 50 a within the tubes 6 of the tube bundle 7. Supply of exhaust to and discharge of exhaust from the tube bundle 7 is realized via the end caps 12, 13. A cooling fluid flows via a inlet as well as an outlet through a chamber as formed by the base tube 2, 20, 20 a and the tube plates 3 and sweeps about the individual tubes 6, using appropriate baffles (not shown) for example. The cooling fluid is provided for a heat exchange with the exhaust to cool the exhaust for example. The surface area formed by the tubes 6 is large and effects a continuous equalization of the temperature differentials between the exhaust and the cooling fluid flowing within the heat exchanger 1, 50, 50 a.

While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. For example, a heat exchanger according to the present invention can be used for various applications. In addition to cooling a fluid, a heat exchanger according to the present invention may be used for recovery of heat or for heating purposes.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: 

1. A heat exchanger for an internal combustion engine, comprising: a base tube having opposite ends; tube plates respectively provided at the ends of the base tube; and a ring embracing the base tube, said ring being made of sheet metal and having legs extending toward one another in a V-shaped manner.
 2. The heat exchanger of claim 1, wherein the ring has a contour which follows a contour of the base tube.
 3. The heat exchanger of claim 1, wherein at least one of the legs bears flatly upon the ring.
 4. The heat exchanger of claim 1, wherein the ring is arranged between the tube plates.
 5. The heat exchanger of claim 1, wherein the ring has a bridge to connect first ends of the legs to one another.
 6. The heat exchanger of claim 1, wherein the ring has a circular ring shaped configuration.
 7. The heat exchanger of claim 5, wherein the legs have bridge-distal second ends having flanges pointing away from one another.
 8. The heat exchanger of claim 1, wherein the ring is connected to the base tube by a material joint.
 9. The heat exchanger of claim 1, wherein the ring is formed out of the base tube.
 10. The heat exchanger of claim 1, further comprising an end cap arranged in a region of one of the tube plates.
 11. The heat exchanger of claim 10, wherein the end cap has an outwardly directed rim.
 12. The heat exchanger of claim 11, further comprising a detachable tension element embracing the rim of the end cap.
 13. The heat exchanger of claim 11, further comprising a circumferential sealing element arranged between the rim and the ring.
 14. The heat exchanger of claim 12, wherein the tension element has a substantially V-shaped configuration in cross section and has a free end which grips around one of the legs of the ring and the rim of the end cap bearing on the other one of the legs.
 15. The heat exchanger of claim 12, wherein the tension element has an open ring shape to define two ends, and further comprising a detachable connection element to connect the two ends of the tension element.
 16. The heat exchanger of claim 15, wherein the detachable connection element is configured as a screw fastener whereby turning of the screw fastener in a first direction decreases a circumference of the tension element and turning of the screw fastener in a second direction in opposition to the first direction decreases the circumference of the tension element. 